Closes #527 | Add Dataloader MDIA

[akhdanfadh]

Closes #527

I implemented one config per language/subset. Thus, configs will look like this: mdia_ind_dialogue_source, mdia_tgl_eng_seacrowd_t2t, etc. When testing, pass mdia_<subset> to the --subset_id parameter.

Note: this dataset can be used for two tasks and both use the same t2t schema with different implementation.

Checkbox

• [x] Confirm that this PR is linked to the dataset issue.
• [x] Create the dataloader script seacrowd/sea_datasets/my_dataset/my_dataset.py (please use only lowercase and underscore for dataset naming).
• [x] Provide values for the _CITATION, _DATASETNAME, _DESCRIPTION, _HOMEPAGE, _LICENSE, _URLs, _SUPPORTED_TASKS, _SOURCE_VERSION, and _SEACROWD_VERSION variables.
• [x] Implement _info(), _split_generators() and _generate_examples() in dataloader script.
• [x] Make sure that the BUILDER_CONFIGS class attribute is a list with at least one SEACrowdConfig for the source schema and one for a seacrowd schema.
• [x] Confirm dataloader script works with datasets.load_dataset function.
• [x] Confirm that your dataloader script passes the test suite run with python -m tests.test_seacrowd seacrowd/sea_datasets/<my_dataset>/<my_dataset>.py.
• [ ] If my dataset is local, I have provided an output of the unit-tests in the PR (please copy paste). This is OPTIONAL for public datasets, as we can test these without access to the data files.

[akhdanfadh]

@MJonibek @danjohnvelasco Done reformatting!

[holylovenia]

I'm merging this since both @MJonibek and @danjohnvelasco's reviews have been addressed. Thank you so much for your work, @akhdanfadh!! 👍